math/algebra

Use the exponential decay equation, to find the half-life of a material that decays from 40mg to 30mg in 10 hours.

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  1. 30 = 40e^10k
    .75 = e^10k
    10k = ln.75
    k = ln.75/10 = -.028768

    then
    1/2 = e^-.028768t
    - .028768t = ln .5
    t = ln .5/-.028768 = 24.09

    the half-life is appr. 24.1 hours

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